Syndet soap bars having improved properties

Abstract

 The invention relates to syndet soap cakes (soap bars) contai­ning, in addition to the usual components, from about 0.001 to about 10% by weight of perfluoropolyethers having perfluo­roalkyl end groups. Among the suitable perfluoropolyethers are those which contain one or more perfluorooxyalkylene units selected from (CF₂-CF₂O), (CF₂O), (C₃F₆O), (CF₂O-CF₂-CF₂O), (CF₂-CF₂-CF₂O),

and

wherein the groups R_fIII are fluorine atoms or perfluoroalkyl groups.

Description

[0001] The present invention relates to syndet soap cakes (soap bars) having improved properties.

[0002] It is known that syndet soap cakes, also called "syndets" or "non-soap soaps", are based on solid synthetic detergents.

[0003] As compared to the soap cakes manufactured from natural soap, they show several advantages. However, their use and manufac­turing suffer from drawbacks. The first drawback is the forma­tion of clefts (cracks) in the soap cakes during their use; besides being disadvantageous from an aesthetical point of view, this alteration may lead to a completely broken product.

[0004] Secondly, the preparation of the syndet soap cakes, which is carried out on facilities designed for the processing of re­latively flexible products, such as natural soap, is diffi­cult, owing to the higher stiffness of syndet soaps.

[0005] One object of the present invention is to provide syndet soaps which do not or only to a limited extent show cracking pheno­mena.
A further object of the present invention is to facilitate the preparation of syndet soap cakes.

[0006] It has now surprisingly been found that the addition to the syndet formulation of small amounts of perfluoropolyethers having perfluoroalkyl end groups eliminates or strongly redu­ces the phenomena of soap cake cleaving (cracking) and facili­tates the preparation of said soap cakes in that it secures a greater ease of homogenization of the composition in paste form, and makes it easier to be extruded and moulded.

[0007] Therefore, the present invention provides syndet soap cakes containing, in addition to the usual components of said soap cakes, from about 0.001 to about 10% by weight of one or more perfluoropolyethers having perfluoroalkyl end groups.

[0008] The perfluoropolyethers having perfluoroalkyl end groups, i.e. without functional groups, are well-known compounds which are described, together with corresponding methods of preparation, in various documents, e.g., in GB-A-1,104,482; US-A-3,242,218; 3,665,041; 3,715,378 and 4,532 039; EP-A-148,482, 151,877 and 191,490 and in international patent applications WO 87/00538 and WO 87/02992.

[0009] Examples of suitable perfluoropolyethers are those which are characterized by the presence of one or more perfluorooxyal­kylene units selected from

a) (CF₂-CF₂O),

b) (CF₂O)

c) (C₃F₆O), a simplified formula for

d) (CF₂O-CF₂-CF₂O),

e) (CF₂-CF₂-CF₂O),

f)

and

g)

wherein the groups R_fIII, the same or different from each other, are fluorine atoms or (preferably C₁₋₃-) perfluoroalkyl groups (e.g. CF₃, C₂F₅ and C₃F₆).

[0010] Perfluoropolyethers suitable for use in the present invention preferably contain one or more of the following individual perfluorooxyalkylene units or combinations of perfluorooxy­alkylene units:

(I) (CF₂-CF₂O) and (CF₂O), said units being randomly distri­buted along the perfluoropolyether chain;

(II)

and (CFXO),
wherein X is F or CF₃, said units being randomly distributed along the perfluoropo­lyether chain;

(III) (CF₂-CF₂O),

and (CFXO),
wherein X is F or CF₃, said units being randomly distri­buted along the polyfluoropolyether chain;

(IV)

(V) (CF₂-CF₂-CF₂O);

(VI) (CF₂-CF₂O);

(VII)

wherein the groups R_fIII, the same or different from each other, are fluorine atoms or (preferably C₁₋₃-) perfluoroalkyl groups; and

(VIII) (CF₂O-CF₂-CF₂O).

[0011] Also suitable are perfluoropolyethers which contain perfluoro­oxetane rings of formula

or

wherein
T, B and R, the same or different from each other, are per­fluorooxyalkyl, perfluoropolyoxyalkyl or perfluoroalkyl radi­cals, and
A is a perfluorooxyalkyl, perfluoropolyoxyalkyl or perfluoro­alkyl radical.

[0012] Examples of perfluoroalkyl radicals are CF₃, C₂F₅ and C₃F₉ while examplary perfluorooxyalkyl radicals are those given above under (a) to (g), terminated with a F atom. Suitable perfluoropolyoxyalkyl radicals include those composed of one or more units given above under (a) to (g), also terminated by a F atom.

[0013] Examples of suitable perfluoropolyethers containing perfluoro­oxyalkylene units are those belonging to the following classes:

A)

wherein:
R_f and R′_f,      the same or different from each other, are se­lected from CF₃, C₂F₅ and C₃F₇;
the units in brackets are randomly distributed along the polyether chain;
a      is an integer; and
b and c      represent integers or zero; the ratio a/(b+c) ranging from 5 to 40 when the sum (b+c) is dif­ferent from zero;

B) CF₃O-(C₂F₄O)_d(CF₂O)_e-CF₃
wherein the C₂F₄O and CF₂O units are randomly distributed along the polyether chain; d and e are integers; and the ratio d/e ranges from 0.3 to 5;

C) CF₃O-(C₃F₆O)_f(C₂F₄O)_g(CFXO)_h-CF₃
wherein the C₃F₆O, C₂F₄O and CFXO units are randomly dis­tributed along the polyether chain;
X is F or CF₃;
f, g and h are integers;
the ratio f/(g+h) ranges from 1 to 50; and
the ratio g/h ranges from 1 to 10;

D) R³_fO-(CF₂CF₂CF₂O)_jR⁴ _f
wherein R³_f and R⁴_f, the same or different from each other, represent -CF₃ or -C₂F₅ and j is an integer.

[0014] The perfluoropolyethers suitable for use in the present in­vention preferably have an average molecular weight of from about 800 to about 20,000, and, even more preferred of from about 1,500 to about 10,000.

[0015] The concentration of perfluoropolyether in the formulation preferably ranges from about 0.1 to about 2% by weight.

[0016] The perfluoropolyethers usually are added to the syndet formu­lation before the latter is homogenized.

[0017] Syndet soap cake pieces may be prepared as follows: As the starting formulation, a syndet base composition in powder form is used. Said base composition is mixed with water, perfluoro­polyethers and other usual additives, and then the whole mix­ture is homogenized. The product is extruded in the form of rods, which rods are cut whereafter the syndet soap cake pie­ces are moulded on an automatic press.

[0018] The perfluoropolyethers employed according to the present in­vention show a perfect compatibility with the other components of the soap cake, and do not modify the physico-chemical cha­racteristics of the aqueous solutions of syndet soap cakes to any significant extent.

[0019] As the remaining components of the syndet soap cakes according to the present invention all of the usual components of said soap cakes can be used.

[0020] For example, as solid surfactants the following products may be employed:

a′) isethionates, i.e., condensation products of a fatty acid of from 12 to 18 carbon atoms with sodium isethionate;

b′) taurates, i.e., N-methyl-taurine amides of fatty acids of from 12 to 18 carbon atoms;

c′) sulfates of fatty alcohols of from 12 to 18 carbon atoms;

d′)sulfosuccinates of fatty alcohols of from 12 to 18 carbon atoms.

[0021] The preferred organic acids used in order to adjust the pH of the aqueous solution of the soap cake at the desired value, are lactic acid and stearic acid.

[0022] All of the common plasticizers, such as, e.g., fatty acids, esters and alkanolamides thereof, fatty alcohols and paraffins, can be also used. Conventional fillers, such as polysaccharides and talc, can be used as well.

[0023] Pigments, perfumes and active principles may also be added.

[0024] The addition of the perfluoropolyethers according to the pre­sent invention considerably improves the properties of the syndet soap cakes in that the resulting soap cakes do not show the phenomenon of cracking during use or, at least, show said phenomenon to a very limited extent only.

[0025] Moreover, in the preparation of soap cakes, the paste-like composition is easier to homogenize, and can easier be extru­ded and moulded.

[0026] The following examples are given in order to illustrate the present invention without, however, limiting it.

EXAMPLE 1

[0027] Several samples of syndet soap cakes were prepared, which samples contained perfluoropolyethers according to the present invention (samples 2, 3, 5 and 6). For comparative purposes, syndet soap cakes which did not contain any perfluoropoly­ethers (samples 1 and 4 ), were also prepared.

[0028] The following perfluoropolyethers, manufactured by Montefluos, were used:

a) Fomblin® HC/04, having an average molecular weight of about 1,500 and a viscosity of 35 cSt at 20°C;

b) Fomblin® HC/25, having an average molecular weight of about 3,200 and a viscosity of 250 cSt at 20°C;

c) Fomblin® HC/R, having an average molecular weight of about 6,600 and a viscosity of 1,500 cSt at 20°C.

[0029] All of the above commercial products may be represented by the formula:

wherein n/m is from 20 to 40.

[0030] Two types of syndet base compositions were used:
1. A composition containing from 80 to 87% of sodium (cocoanut acid) isethionate;
2. Zetesap® 813A, by Zchimmer and Schwarz, containing the fol­lowing components:

combination of sulfates and sulfo-succinates of fatty alcohols of from 12 to 18 carbon atoms	50% b.w.
polysaccharides	23% b.w.
plasticizers	23% b.w.
water and other ingredients	up to 100% b.w.

[0031] Six samples (1 to 6) were prepared; their composition is shown in Table 1 below.

[0032] On a 5% b.w. aqueous solution of each of said samples the con­ductivity X, the pH value and the surface tension γsup were determined at 25°C. The obtained results are reported in Table 1.

[0033] A comparison of the samples with and without various Fomblin® HC grades shows that the addition of the perfluoropolyether to the syndet soap cake formulation does not modify the physi­co-chemical characteristics thereof to any significant ex­tent.

TABLE 1

Sample Number	Composition		X (mS)	pH	γsup (dyne/cm)
1	Zetesap® 813 A	100 %	3	7.10	30.3
2	Zetesap® 813 A	99.5%	3.4	7.10	32.4
	Fomblin® HC/25	0.5%
3	Zetesap® 813 A	98 %	2.9	6.55	31.0
	Fomblin® HC/25	1 %
	Perfume	1 %
4	Sodium cocoanut acid		3.2	6.63	30.2
	isethionate (80-87%)	50 %
	Zetesap® 813 A	50 %
5	Sodium cocoanut acid		3	6.51	30.3
	isethionate (80-87%)	50 %
	Zetesap® 813 A	49 %
	Fomblin® HC/25	1 %
6	Sodium cocoanut acid		2.9	5.80	31.0
	isethionate (80-87%)	50 %
	Zetesap® 813 A	49.4%
	Fomblin® HC/25	0.4%
	Fomblin® HC/R	0.2%

EXAMPLE 2

[0034] The present example describes a comparative test with respect to accelerated ageing during use of a syndet soap cake contai­ning Fomblin® HC/25 (sample 2 of example 1) and of a similar syndet soap cake not containing any perfluoropolyethers(sample 1 of example 1).

[0035] The accelerated ageing of the soap cakes was simulated by hol­ding said soap cakes (weight about 25 g) under running tap water for 4 hours at room temperature and then leaving them standing for 24 hours in a ventilated oven at 30°C. Said treat­ment was repeated over 8 days.

[0036] After the above treatment, a significant difference was ob­served between the two tested samples. On the surface of the reference sample a larger number of more visible alterations was observed: bubbles, slight or small-size but deep clefts or cracks; said reference soap cake additionally was affected by large cracks at its edges. Furthermore, by measuring the weight loss, it was determined that a larger amount of the reference soap cake had been dissolved: in fact, 64% of the reference sample had dissolved, as compared to 49% of the sample which contained Fomblin® HC/25.

[0037] A photograph of the soap cakes after the test, at a magnifica­tion of 2.5X, is shown in Figure 1. The right-hand side soap cake is the one which contained Fomblin® HC/25; the left-hand soap cake is the reference sample which did not contain per­fluoropolyether.

[0038] The above mentioned alterations can be observed in the refe­rence sample.

EXAMPLE 3

[0039] The present example relates to an accelerated ageing test wherein a syndet soap bar containing Fomblin® HC/25 (sample 7) and a similar (comparative) syndet soap bar not containing any perfluoropolyether (sample 8) were employed.

[0040] Sample 7 had the following composition:

- sodium cocoanut acid isethionate (80-87%)	17 parts b.w.
- fats, plasticizers and binders	78 parts b.w.
- Fomblin® HC/25	0.5 parts b.w.
- water	5 parts b.w.

[0041] Sample 8 had the following composition:

- sodium cocoanut acid isethionate (80-87%)	17 parts b.w.
- fats, plasticizers and binders (the same as in sample 7)	78 parts b.w.
- water	5 parts b.w.

[0042] An accelerated ageing was simulated on the two bars (weight about 75 g) by holding them under running tap water for 4 hours at room temperature and then leaving them standing for 24 hours in a ventilated oven at 30°C; said treatment was repeated over 8 days. A photograph of the bars after the test is shown in Figure 2. The bar on the right is the one containing Fomblin® HC/25, the bar on the left is the comparison sample not containing perfluoropolyether. Big cracks are present in the latter sample.

Claims

1. Syndet soap cakes containing, in addition to the usual com­ponents of said soap cakes, from about 0.001 to about 10% by weight of one or more perfluoropolyethers having per­fluoroalkyl end groups.

2. Syndet soap cakes according to claim 1, characterized in that the perfluoropolyethers contain one or more perfluoro­oxyalkylene units selected from:

a) (CF₂-CF₂O)

b) (CF₂O)

c) (C₃F₆O)

d) (CF₂O-CF₂-CF₂O)

e) (CF₂-CF₂-CF₂O)

f)

and

g)

wherein the groups R_fIII, the same or different from each other, represent fluorine atoms or perfluoroalkyl groups.

3. Syndet soap cakes according to any one of claims 1 and 2, characterized in that the perfluoropolyethers contain one or more individual perfluorooxyalkylene units or combina­tions of perfluorooxyalkylene units selected from:

I) (CF₂-CF₂O) and (CF₂O), said units being randomly distri­buted along the perfluoropolyether chain;

II)

and (CFXO),
wherein X is F or CF₃, said units being randomly distributed along the perfluoropolyether chain;

III) (CF₂-CF₂O),

and (CFXO),
wherein X is F or CF₃, said units being randomly dis­tributed along the perfluoropolyether chain;

IV)

V) (CF₂-CF₂-CF₂O);

VI) (CF₂-CF₂O);

VII)

wherein the groups R_fIII, the same or different from each other, are fluorine atoms or perfluoroalkyl groups; and

VIII) (CF₂O-CF₂-CF₂O).

4. Syndet soap cakes according to any one of claims 1 to 3 characterized in that the perfluoropolyethers contain per­fluorooxetane rings of formula:

or

wherein:
T, B and R,      the same or different from each other, are per­fluorooxyalkyl, perfluoropolyoxyalkyl or perfluo­roalkyl radicals, and
A      is a perfluorooxyalkyl, perfluoropolyoxyalkyl or perfluoroalkyl radical.

5. Syndet soap cakes according to one or more of the preceding claims, characterized in that the perfluoroalkylpolyethers have an average molecular weight of from about 800 to about 20,000.

Drawing